Tailstock Tool Storage

[akjeff]

This is completely unimportant I'm sure. But what is this thing I circled?

It's a tool holder with a mounting arm in it, for an indicator. I think the angle makes it look strange, and there was no indicator in it at the time. Edit, Dark Zero beat me to it! That's exactly what it is!

 

[Dabbler]

those holders are commonly used ine height gauges and in the old American rocker tool post.